1. Field of the Invention
This invention relates generally to battery charge measurement techniques, and more particularly, to a method of interrupting and dynamically switching ranges to improve battery charge measurement range in a sigma delta converter.
2. Description of the Prior Art
Consumers are continually frustrated with not knowing the exact amount of battery life remaining in their portable applications. An accurate charge reading tells the user precisely how much operating or standby time remains before the battery runs down, or how much time it will take for the battery to reach full charge. Further, the system can use charge information as an input to power management routines to more efficiently manage battery power versus user demand of system resources and peripherals.
In view of the foregoing, it would be desirable and advantageous to provide a technique of extending system operating time associated with portable applications beyond that available using presently known techniques for managing battery charge.
The present invention is directed to a method of improving the battery charge measurement range in a sigma delta converter associated with portable applications such as a cell phone.
In one aspect of the invention, a method of improving the battery charge measurement range in a sigma delta converter associated with portable applications is implemented by interrupting the sigma delta modulator and changing a reference voltage and measurement time to allow integrated current to occur over a wider dynamic range.
In another aspect of the invention, a method of improving the battery charge measurement range in a sigma delta converter associated with portable applications is implemented by using the transmit enable signal to be used to change the range of the sigma delta modulator dynamically to capture a large current pulse without causing error.
In yet another aspect of the invention, a method of improving the battery charge measurement range in a sigma delta converter associated with portable applications is implemented to maintain accurate integration of the current by adding the partial results of an interrupted measurement to the charge accumulator.
In still another aspect of the invention, a method of improving the battery charge measurement range in a sigma delta converter associated with portable applications is implemented to maintain accurate integration of the current when the transmit pulse exceeds the maximum sigma delta range by adding the partial results of an interrupted measurement to the charge accumulator, and then switching the dynamic range back to a standby range.